This week, Catholic cardinals are gathering in the world's smallest country to set about the task of making the biggest news on earth. Their job: choose the leader of the world's largest Christian faith. Under the soaring work of Michelangelo in the Sistine Chapel, they will consider the future of a troubled church at a conclave expected to begin within days.

We don't know exactly what happens in these secretive meetings, if there's yelling or note-passing, moments of laughter, or hours of tedium. But it is clear that certain things are verboten, at least if they're blatant: politicking, horse-trading, and self-promotion.

For answers, I turned to Frederic J. Baumgartner, professor of history at Virginia Tech and author of 2003's "Behind Locked Doors: A History of Papal Elections."

Q: A conclave is actually a form of democracy, isn't it? How did popes begin to be chosen by a group of men?

A: In the early church, the Christian community as a whole chose the bishop. It wasn't a process of election as such, or at least what we'd call an election. It was a system of acclamation. Someone said, "I'd like to be bishop," and they were chosen by consensus.

Over time, it evolved into a system in which the clergy of the city had the right to choose the bishop. The problem was that once the Holy Roman Empire became powerful, it was able to manipulate the clergy. In the 900s and early 1000s, the choice was really that of the emperor: He chooses the pope and the clergy does the rubber stamping.

The decision was made in 1059 to take the clergy of Rome out of the system and have the chief bishops of Italy do the choosing, primarily as a way of reducing the Holy Roman emperor's influence. But his influence was never eliminated by any means until the disappearance of the Austrian emperor after World War I.

Q: How influential were the wishes of Catholic rulers from powerful countries like France and Spain?

A: They had the right of exclusion. There were times when cardinals came up from Paris or Madrid or Vienna with a list of cardinals that their rulers would not accept.

There were always those cardinals who said, 'We shouldn't pay any attention to those guys.' But a majority of cardinals agreed there would be too much of a schism if they supported someone who was opposed by a Catholic ruler.

Q: We know about the many craven popes of the distant past. How did this system produce such scoundrels?

A: Certainly part of the problem was the choices: They were choosing bad popes because they had bad cardinals.

Renaissance cardinals were basically Renaissance popes in miniature, little different than the popes they elected. They were wealthy, had children, and politicked like crazy in their city states, kingdoms, or countries.

They were basically making bad choices because there was nothing to choose from but bad choices. There were two popes in the 16th century who were pious men and outside the realm of Renaissance popes, but they both had short reigns.

Q: How does the voting work now?

A: You have to get a two-thirds majority. And you can't vote for yourself.

The way they used to check on that has disappeared, so that may not be enforceable anymore. You used to have to put a motto on your ballot, and they'd check it. The story is that when Benedict XV became pope [in 1914], he was elected by the minimum number. One cardinal demanded that the ballots be checked to make sure he didn't vote for himself, and that apparently deeply offended him.

Q: What if it takes a long time to reach a conclusion?

A: It's taken years, actually, and once it took three years to elect a pope. They finally locked the cardinals in a palace to force them to make a decision. And when they still didn't make a decision, the local people are supposed to taken the roof off the palace. Someone humorously said it was to let the holy spirit in.

Q: Could that happen this time? Could they take off the roof?

A: They'd probably do too much damage to the Sistine Chapel.

Q: Good point. How do the cardinals make choices if politicking is frowned upon?

A: They can't openly politick for each other or themselves. A cardinal can't go have a dinner meeting with three or four of his fellow cardinals and say, "Vote for me," and one of his friends can't do that. That kind of open politicking is specifically barred.

What you can do is talk about the cardinals and what their beliefs and opinions are. Someone like Cardinal George of Chicago who doesn't spend much time in Rome might be talking to someone who's based in the curia to find out about the strong candidates, what their views are, what their health is, whether they are strong or vigorous enough to do the job.

A lot of these guys may be seriously ill or have debilitating disease, which would make it difficult for them to be pope.

Q: How about the kind of you-scratch-my-back-and-I'll-scratch-yours kind of politics that we're so familiar with here in the US?

A: You can't horse-trade, at least openly. You can't say, "If you make me secretary of state, I'll vote for you." But you can find out from a friend of cardinal what he thinks about you and who he thinks might make strong possible choices as secretary of state.

Q: Has a conclave ever occurred during as much of a crisis atmosphere as the church is facing today?

A: There have been certainly been times when the papacy and church were in the midst of a serious crisis at the time of a conclave.There have been times when France and Spain, both Catholic countries, have been at war with each other. And the elections of the 16th century occurred during the Reformation. One could argue that the conclave of 1534 took place during a much more serious state of crisis because of the threat of the Reformation and the issue of how to respond to it.

Q: How will things be different now considering that the previous pope is still living?

A: The fact that he's still alive has got to have some impact on their voting and their balloting, But I think Benedict will make every effort at not influencing the election. To the extent that he really will is a different question entirely. It's one thing to vote for someone who wasn't in the graces of the previous pope when he's dead. But when he's alive, it might be quite different.

Q: What are some of the issues raised by the existence of a former pope?

A: One of the objections to popes abdicating or resigning is that he'll still be around. When the new pope changes policy, there could easily be a schism within the church by those who insist on the old pope's point of view.

Q: How much influence do the Italian cardinals have over the process?

A: They have a home-field advantage and the biggest voting bloc. It was a bit surprising when two popes in a row were elected who weren't Italians.The real question is whether there are any Italian cardinals who are respected enough to be elected. I expect there are.

Q: What are the strengths of the system as it is?

A: The official position about why they do it this way is it give a sense of mystery to outsiders, which is never a bad thing. Being too transparent ends up being a problem. And this way covers up the politics that do take place. A cardinal would tell you it provides an atmosphere in which the holy spirit is free to operate. The truth of the matter is that, far too often, the holy spirit could have hardly been present considering what happened.

Q: Do you think the process is a good one in modern times?

A: For the most part, they've elected decent men as popes in the last several hundred years. The system has continued to work reasonably well. But speaking as a historian, I would dearly love to get the information about what happened in the conclave, at least a couple years after it was over. From that point of view, the system works too well.

[Curious about the last time a pope resigned? Read my Q&A interview with historian Jon M. Sweeney, author of 2012's "The Pope Who Quit: A True Medieval Tale of Mystery, Death, and Salvation." For more on the history of Christianity, check my interviews with religious scholars Elaine Pagels ("Revelations: Visions, Prophecy, and Politics in the Book of Revelation"), Bart Ehrman ("Did Jesus Exist?: The Historical Argument for Jesus of Nazareth"), and Adam C. English ("The Saint Who Would Be Santa Claus: The True Life and Trials of Nicholas of Myra").]